Women's Health Blood Test After 40: Essential Markers to Check

For women, 40 is not just a milestone birthday — it is a biological inflection point. Perimenopause typically begins in the early to mid-forties, thyroid disorders become significantly more common, cardiovascular protection from oestrogen starts to wane, and bone density loss quietly accelerates. The NHS does not routinely screen for most of these changes, which means women are left to navigate symptoms with little objective data unless they take the initiative.

What changes in a woman's body after 40

Perimenopause: the hormonal transition

Perimenopause — the transitional phase before menopause — typically lasts 4 to 8 years and begins, on average, around age 44. During this time, ovarian function becomes irregular. Progesterone production drops first (because more cycles become anovulatory), while oestradiol fluctuates wildly before its eventual decline.

Common symptoms include irregular periods, hot flushes, night sweats, mood changes, brain fog, insomnia, joint pain and reduced libido. The difficulty is that these symptoms overlap with thyroid dysfunction, iron deficiency, vitamin D insufficiency and stress — making a blood test essential for distinguishing between them.

Key hormonal markers during perimenopause:

• FSH (follicle-stimulating hormone): Rises as ovarian reserve declines. An FSH above 25 IU/L on day 2–5 of the cycle strongly suggests perimenopause. Above 40 IU/L is consistent with menopause.
• Oestradiol: Fluctuates unpredictably. A single low reading (below 100 pmol/L) alongside elevated FSH supports the perimenopausal picture.
• LH (luteinising hormone): Rises alongside FSH but is less reliable as a standalone marker.
• Progesterone: A day 21 progesterone below 5 nmol/L confirms anovulation — one of the earliest signs of perimenopause.

Thyroid — the overlooked epidemic

One in eight women will develop a thyroid disorder in her lifetime, and the risk increases markedly after 40. Hashimoto's thyroiditis (autoimmune hypothyroidism) is the most common cause, affecting roughly 5% of women over 40 in the UK. It often begins insidiously — fatigue, weight gain, dry skin, hair thinning, low mood — symptoms easily attributed to perimenopause or "just getting older."

A comprehensive thyroid panel should include:

• TSH: 0.27–4.2 mIU/L is the reference range, but emerging consensus suggests that TSH above 2.5 mIU/L with symptoms warrants further evaluation.
• Free T4: 12–22 pmol/L. Low-normal Free T4 with rising TSH indicates the thyroid is struggling.
• Free T3: 3.1–6.8 pmol/L. Some women have adequate T4 but poor conversion to the active T3 form.
• Anti-TPO and Anti-TG antibodies: Positive antibodies confirm autoimmune thyroiditis, even if TSH is still "normal." This is important because it predicts future thyroid failure and may warrant monitoring or early intervention.

Cardiovascular risk — the oestrogen cliff

Before menopause, oestrogen provides significant cardiovascular protection by maintaining endothelial function, keeping LDL lower and HDL higher, and improving insulin sensitivity. As oestrogen declines through perimenopause, this protection diminishes. By 55, women's cardiovascular risk equals that of men — and cardiovascular disease is the number one killer of women in the UK, accounting for more deaths than all cancers combined.

A full lipid panel is essential: total cholesterol, LDL, HDL, triglycerides and non-HDL cholesterol. Women who had excellent cholesterol at 35 may see significant shifts by 45 as the oestrogen buffer erodes. HbA1c should be checked simultaneously — insulin resistance often develops in tandem with hormonal changes, and the two compound cardiovascular risk.

Bone health

Women lose bone density at approximately 1% per year from the mid-thirties, but this accelerates to 2–3% per year in the 5 years surrounding menopause due to declining oestrogen. By 50, 1 in 2 women over 50 will experience an osteoporotic fracture in their remaining lifetime. Blood tests cannot measure bone density directly (that requires a DEXA scan), but they can assess the metabolic environment affecting bone:

• Vitamin D: Essential for calcium absorption. Below 50 nmol/L impairs bone mineralisation.
• Calcium: Adjusted calcium should sit between 2.2 and 2.6 mmol/L.
• Thyroid function: Both hyper- and hypothyroidism affect bone turnover.
• Oestradiol: Low levels directly correlate with accelerated bone loss.

Iron — a shifting target

Iron needs change significantly through a woman's forties. In perimenopause, heavier and more frequent periods can deplete iron stores rapidly — ferritin below 15 µg/L is common and causes fatigue that compounds perimenopausal exhaustion. After menopause, iron loss through menstruation stops entirely, and some women see ferritin climb. Excessively high ferritin (above 200 µg/L in post-menopausal women) warrants investigation for haemochromatosis or inflammatory conditions.

A full iron panel — ferritin, serum iron, transferrin saturation and TIBC — captures the full picture at any stage.

The complete over-40 women's panel

Bringing it all together, a thorough annual blood test for women over 40 should include:

• Hormones: FSH, LH, Oestradiol, Progesterone, Testosterone, SHBG
• Thyroid: TSH, Free T4, Free T3, Anti-TPO, Anti-TG
• Cardiovascular: Total Cholesterol, LDL, HDL, Triglycerides, Non-HDL, HbA1c
• Vitamins and minerals: Vitamin D, Active B12, Folate, Ferritin, Iron Studies
• Liver and kidney function: ALT, ALP, GGT, Bilirubin, Albumin, Creatinine, eGFR
• Full blood count

Recommended Lola Health tests

• Female Hormones Clarity 31 — £115 — 31 biomarkers covering the hormonal, thyroid and cardiovascular picture in a single panel. Includes FSH, LH, oestradiol, progesterone, testosterone, SHBG, full thyroid with antibodies, lipid panel and key vitamins. This is the purpose-built test for women navigating perimenopause who want hormone and thyroid answers alongside cardiovascular screening.
• Core Health 45 — £120 — Broader coverage across 45 biomarkers including liver, kidney, HbA1c, B12, vitamin D, iron studies, thyroid and full blood count. Ideal as a comprehensive annual screen that captures metabolic and organ function alongside the basics.
• Peak Insights 70 — £185 — The most extensive panel: 70 biomarkers covering everything above plus additional markers. If you want the most thorough single test available and prefer not to wonder whether you missed something, this is the one.

When to test

If you are still having regular periods, test hormones on day 2–5 of your cycle (FSH, LH, oestradiol) and again on day 21 (progesterone). If your cycle has become irregular — a hallmark of perimenopause — test on any day. The irregularity itself is informative.

For all other markers (thyroid, lipids, HbA1c, vitamins, liver, kidney), timing within the cycle does not matter. A fasting morning blood draw gives the most accurate lipid and glucose readings.

What your GP will and will not do

NHS guidelines do not recommend routine hormone testing for perimenopause in women over 45 if symptoms are present — the NICE guideline (NG23) states that diagnosis should be clinical. In practice, this means many women are told they are "probably perimenopausal" without any blood work to confirm or rule out thyroid disease, iron deficiency or other mimics. Private testing fills this gap, giving you objective data to take to your GP — or to act on independently with informed supplement and lifestyle choices.

Taking control of the transition

The forties are not a decline — they are a transition. But transitions require information. A comprehensive blood test once a year gives you the data to distinguish between perimenopause and thyroid disease, between normal ageing and early cardiovascular risk, between fatigue from low iron and fatigue from something more serious. It is the most efficient investment in your health during a decade when your body is changing faster than at any point since puberty.